Beta-glucans are a group of β-D-glucose polysaccharides that are produced by bacteria, yeast, algae, fungi, and in cereals. The properties of the beta-glucans depend on the source, for example, whether from bacteria, algae, yeast or other sources. Usually beta-glucans form a linear backbone with 1,3 beta-glycosidic bonds. It is known that incorporating beta-glucans within a human or animal diet has advantages. Some beta-glucans may aid in immune modulation and decrease the levels of saturated fats and reduce the risk of heart disease. It is also known that different types of beta-glucans have different effects on human physiology. For example, cereal beta-glucans may affect blood glucose regulation in those having hypercholesterolemia, while mushroom beta-glucans may act as biological response modifiers on the immune system. In some cases, it has been found that yeast beta-glucans may decrease levels of IL4 and IL5 cytokines that relate to allergic rhinitis and increase the levels of IL12.
It has also been determined that Euglena gracilis biomass containing paramylon (beta-1,3-glucan) can enhance the immune function of an individual. Paramylon is a linear (unbranched) beta-1,3-glucan polysaccharide polymer with a high molecular weight. This unbranched polymer is distinct from the other beta-glucans such as the branched beta-(1,3; 1,6)-glucans from the cell walls of yeast and cereals, for example, oats and barley; and branched beta-1,3-glucans with beta-(1,4)-glycosidic bonds forming polysaccharide side chains such as found in mushrooms.
An advantage of the beta-glucan from Euglena is that it lacks beta-(1,6), beta(1,4), and beta(1,2) bonds and any side branching structures. As a molecule and similar to some other glucans that have branching, this linear beta-glucan is insoluble and believed to be homogenous and have higher combined localization and binding affinities for receptors involved in immune response. Paramylon may be obtained from Euglena gracilis algae, which is a protist organism, and a member of the micro-algae division euglenophyceae within the euglenales family and includes many different autotrophic and heterotrophic species which can also produce paramylon. These protists can be found in enriched fresh waters, such as shallow water rivers, lakes and ponds. Paramylon is an energy-storage compound for the Euglenoids and comparable to the starch or oil and fats in other algae. Paramylon is produced in the pyrenoids and stored as granules in the cytoplasm. The paramylon granules in Euglena gracilis are oblong and about 0.5-2 micrometers (um) in diameter. Euglena gracilis stock cultures are usually maintained in controlled laboratory conditions and used as an initial inoculum source. Euglena gracilis may be manufactured axenically in closed, sterilizable bioreactors. The Euglena gracilis inoculum may be transferred to seed bioreactors to accumulate larger amounts of biomass and then passaged up to larger bioreactors as needed.
It is desirable to scale-up production of such linear, unbranched beta-1,3-glucan from genus Euglena organisms, and more particularly, Euglena gracilis using improved fermentation techniques. Euglena gracilis derived beta-glucan may confer advantageous properties for human and other animal health, including enhanced immune response and other health promoting properties. It is desirable to form a beta-glucan composition that will have enhanced properties for improved immune modulation and other uses.